Back up pad of grinding wheel

ABSTRACT

A back up pad of a grinding wheel includes two glass fiber layers and two carbon fiber layer attached to the glass fiber layer. The glass fiber layers and the carbon fiber layer are thermally compressed. The carbon fiber layer has a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).

FIELD OF THE INVENTION

The present invention relates to a grinding wheel; and, more particularly, to a back up pad of the grinding wheel which is flexible to allow the grinding wheel to grind curved portions and which is relatively thin and light, thereby decreasing the production cost thereof.

BACKGROUND OF THE INVENTION

Generally, a grinding wheel is mounted on a driving machine providing a rotational power thereto, and is used to grind a surface of a workpiece.

FIG. 1 shows a perspective view of a conventional grinding wheel 1 of a so-called lamella or flap type, wherein a plurality of coated abrasives flaps 10 are circumferentially arranged and adhesively attached on a back up pad 20.

Referring to FIGS. 2, 3A and 3B, the back up pad 20 is constructed by thermally compressing a plurality of, e.g., six, glass fiber layers with phenol novolac resin impregnated therein, and includes a central hub 11 for receiving a rotating shaft of a grinder (not shown). The coated abrasives flaps 10 are circumferentially arranged on the back up pad 20 and attached thereto by using an epoxy adhesive. The glass fiber layer each has a net shape with a fabric construction of about 5-16 s/yarn×5-16 s/yarn (warp×fill).

Such a conventional back up pad 20 comprised of the glass fiber layer 22 is relatively thick and heavy, thereby increasing the production cost thereof. Further, the back up pad 20 is not sufficiently flexible to allow the grinding wheel to grind curved portions of a workpiece.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a back up pad of a grinding wheel which is flexible to allow the grinding wheel to grind curved portions and which is relatively thin and light, thereby decreasing the production cost thereof.

In accordance with a preferred embodiment of the present invention, there is provided a back up pad of a grinding wheel including: a plurality of glass fiber layers; and at least one carbon fiber layer attached to the glass fiber layer.

Preferably, two glass fiber layers and two carbon fiber layer are thermally compressed and the carbon fiber layer has a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of a preferred embodiment given in conjunction with the accompanying drawings, in which;

FIG. 1 illustrates a perspective view of a conventional grinding wheel of a flap type;

FIG. 2 depicts a perspective view of a conventional back up pad;

FIG. 3A sets forth a cross sectional view of the conventional back up pad taken along the line A-A of FIG. 2;

FIG. 3B shows an enlarged view of a portion of the conventional back up pad in FIG. 3A;

FIG. 4 illustrates a perspective view of a grinding wheel of a flap type in accordance with the present invention;

FIG. 5 depicts a perspective view of a back up pad in accordance with a preferred embodiment of the present invention;

FIG. 6A presents a cross sectional view of the back up pad taken along the line B-B in FIG. 5; and

FIG. 6B shows an enlarged view of a portion of the back up pad in FIG. 6A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 4, there is illustrated a grinding wheel of a flap type in accordance with a preferred embodiment of the present invention. As shown in FIG. 4, a flap type grinding wheel 100 includes a back up pad 120, and a plurality of coated abrasives flaps 110 circumferentially arranged on the back up pad 120 and attached thereto by using, e.g., an epoxy adhesive.

Referring now to FIGS. 5, 6A and 6B, the back up pad 120 is constructed by thermally compressing a plurality of, e.g., two, glass fiber layers 122 with phenol novolac resin impregnated therein and a plurality of, e.g., two, carbon fiber layers 124. The back up pad 120 includes a central hub 111 for receiving a rotating shaft of a grinder (not shown). A non-woven sheet (not shown) may be attached to the bottom surface of the lowermost carbon fiber layer 124. Further, the coated abrasives flaps 110 are circumferentially arranged on the uppermost glass fiber layer 122 of the back up pad 120 and attached thereto by using an epoxy adhesive. Each of the glass fiber layers 122 has a net shape with a fabric construction of about 5-16 s/yarn×5-16 s/yarn (warp×fill). Each of the carbon fiber layers 124 has a net shape with a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).

In this embodiment, although the glass fiber layers 122 are located above the carbon fiber layers 124 and the coated abrasives flaps 10 are attached to the glass fiber layers 122, the locations of the glass fiber layers 122 and the carbon fiber layers 124 may be exchanged and the coated abrasives flaps 10 are attached to the carbon fiber layers 124. Alternatively, the glass fiber layers 122 and the carbon fiber layers 124 may be alternately stacked. In this case, the non-woven sheet and the coated abrasives flaps are respectively attached to the uppermost glass or carbon fiber layer and the lowermost glass or carbon fiber layer.

A comparison test for the back up pad of the present invention and a conventional back up pad was conducted and the result thereof is shown in Table 1. TABLE 1 Back up pad of the Conventional present invention back up pad (two glass fiber (six glass fiber layers + two carbon layers) fiber layers) Tensile strength 200˜250 250˜300 (Kgf/in²) Toughness against ≧25 ≧30 rotational fracture (sec) Flexibility 6 4

In the above test, the tensile strength was measured by using LLOYD instruments type LR5R tester and the toughness against rotational fracture was measured by rotating the back up pad at 30,000 rpm. Further, in Table 1, the flexibility is the greatest at 1 and the lowest at 10.

As indicated in Table 1, the back up pad of the present invention, which was made by thermally compressing two glass fiber layers and two carbon fiber layers, exhibits superior effects in all of tensile strength, toughness against rotational fracture and flexibility to the conventional back up pad, which was made by thermally compressing six glass fiber layers.

Moreover, since the total number of fiber layers is decreased, the back up pad of the present invention becomes light and easy to handle. In addition, the production cost of the pack up pad is reduced by using the carbon fiber.

Since the back up pad of the present invention has a greater flexibility, it is possible to allow the grinding wheel to grind curved portions which are difficult to be grinded by a grinding wheel employing the conventional back up pad.

While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. 

1. A back up pad of a grinding wheel comprising: a plurality of glass fiber layers; and at least one carbon fiber layer attached to the glass fiber layer.
 2. The back up pad of claim 1, wherein the glass fiber layers and the carbon fiber layer are thermally compressed.
 3. The back up pad of claim 1, wherein the number of the glass fiber layers is two and two carbon fiber layers are attached to the glass fiber layers.
 4. The back up pad of claim 1, wherein the carbon fiber layer has a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).
 5. The back up pad of claim 1, wherein a plurality of coated abrasive flaps are circumferentially arranged on the back up pad.
 6. The back up pad of claim 3, wherein the carbon fiber layers have a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).
 7. The back up pad of claim 3, wherein a plurality of coated abrasive flaps are circumferentially arranged on the back up pad.
 8. The back up pad of claim 3, wherein the back up pad has tensile strength of between 250 and 300 Kgf/in².
 9. The back up pad of claim 1, wherein the glass fiber layers and the carbon fiber layer are thermally compressed; and wherein the number of the glass fiber layers is two and two carbon fiber layers are attached to the glass fiber layers.
 10. The back up pad of claim 9, wherein the carbon fiber layers have a fabric construction of about 40-80 s/yarn×20-35 s/yarn (warp×fill).
 11. The back up pad of claim 9 wherein a plurality of coated abrasive flaps are circumferentially arranged on the back up pad.
 12. The back up pad of claim 9 wherein the back up pad has tensile strength of between 250 and 300 Kgf/in². 